CONICET | Buscador de Institutos y Recursos Humanos

Recent progressive changes that have occurred in the areas of Termas de Copahue and COP-2 well are described. These geothermal active zones are placed near the Copahue Volcano, which is located on the west border of Argentina, in the Neuquén Province, on the Andes Range, nearby the boundary with Chile. An increasing of the activity at the Copahue Volcano has occurred since 1992. The first episode, as mentioned on 1992, was enclosed almost exclusively to the eruption of large amounts of sulphur. On 1995 a second episode of similar characteristics of that of 1992 occurred. On 2000 took place the last and largest episode of volcanic eruption, that extended during almost six months. In this stage, the eruption consisted mainly in magmatic pyroclastic material, with andesitic composition. One of the most conspicuous changes that have been observed until then is the emergence of a new area of geothermal activity on the southern slope of Termas de Copahue. It began with the surging of some fumarolic activity in the area, which has gradually increased, accompanied by the formation of scabs of efflorescence, and followed by the flowing of hot fluids and the development of large mud pots. The other is the presence of a group of minerals that were new for this geothermal field in the area around the geothermal wells, at about 3 km from the previous zone. These minerals are mainly burkeite and hanksite, of the group of sulphate-carbonates, and tinkalconite, which belongs to the class of hydrated borates containing hydroxyl or halogen. It is proposed that these changes would be related to the eruptive activity that the Copahue Volcano had showed in the last sixteen years. This activity would have generated structural as well as physico-chemical variations in the reservoir conditions as a consequence of the activity.